It is known in the automotive vehicle occupant restraint art to provide an air bag in the general proximity of an occupant which inflates in response to an impact signal generated by an impact sensor. Under some circumstances, it has been found desirable to vary the manner in which the restraint is inflated so as to provide an appropriate restraining force. This variation of restraint inflation can be accomplished by moderating the amount of inflation medium, for example, a gas which enters the restraint. It is known to sense various occupant characteristics to assist in determining an appropriate restraint inflation. Such characteristics may include whether an occupant is belted, the belt payout, an occupant weight, a seat incline position, occupant position on a seat, and seat position with respect to the vehicle. These characteristics may be determined by sensors, including for example, ultrasonic position sensors, as disclosed in U.S. Pat. Nos. 5,413,378 and 5,626,359 (both to Steffans, Jr. et al.), and occupant weight sensors and seat back incline angle sensors, as disclosed in U.S. Pat. No. 5,573,269 (Gentry et al.). These systems abstractly refer to a seat position sensor without providing particular embodiments of such.
It is known to provide a linear potentiometer in conjunction with a slidable occupant seat in order to determine seat position, as seen in U.S. Pat. Nos. 5,624,132 (Blackburn et al.) and 5,653,462 (Breed et al.). There is a need, however, for a seat sensing apparatus for use in conjunction with a deployable restraint which is less expensive, more reliable, and easier to install and maintain.